Technical Field
The embodiments of the present disclosure relate to illumination devices, and more particularly to an LED tube lamp compatible with different power sources, and its components including light sources, electronic components, and end caps.
Related Art
LED (“light emitting diode”) lighting technology is rapidly developing to replace traditional incandescent and fluorescent lighting. LED tube lamps are mercury-free in comparison with fluorescent tube lamps that need to be filled with inert gas and mercury. Thus, it is not surprising that LED tube lamps are becoming a highly desired illumination option among different available lighting systems used in homes and workplaces, which used to be dominated by traditional lighting options such as compact fluorescent light bulbs (CFLs) and fluorescent tube lamps. Benefits of LED tube lamps include improved durability and longevity and far less energy consumption; therefore, when considering all factors, they would typically be considered as a cost-effective lighting option.
Electrical ballast is a broader category of ballast that can encompass for example electronic ballast, inductive ballast, and/or emergency ballast. More specifically, common main types of electronic ballast include instant-start ballast and programmed-start ballast. Electrical ballast typically includes a resonant circuit and is designed to match the loading characteristics of a fluorescent lamp in driving the fluorescent lamp. For example, for properly starting a fluorescent lamp, the electrical ballast provides driving methods respectively corresponding to the fluorescent lamp working as a capacitive device before emitting light, and working as a resistive device upon emitting light. But an LED is a nonlinear component with significantly different characteristics from a fluorescent lamp. Therefore, using an LED tube lamp with an electrical ballast impacts the resonant circuit design of the electronic ballast, which may cause a compatibility problem. Generally, a programmed-start ballast detects the presence of a filament in a fluorescent lamp, but traditional LED driving circuits cannot support such detection and may cause a failure of a filament detection and thus may fail to start the LED tube lamp. Further, electrical ballast is in effect a current source, and when it acts as a power supply of a DC-to-DC converter circuit in an LED tube lamp, problems of overvoltage and overcurrent or undervoltage and undercurrent are likely to occur, resulting in damaging of electronic components in the LED tube lamp or unstable provision of lighting by the LED tube lamp.
Further, the driving of an LED uses a DC driving signal, but the driving signal for a fluorescent lamp is a low-frequency, low-voltage AC signal as provided by an AC power line or an inductive ballast, a high-frequency, high-voltage AC signal provided by an electronic ballast, or even a DC signal provided by a battery for emergency lighting applications. Since the voltages and frequency spectrums of these types of signals differ significantly, simply performing a rectification to produce the required DC driving signal in an LED tube lamp is typically not competent at achieving the LED tube lamp's compatibility with traditional driving systems of a fluorescent lamp.
In addition, conventional fluorescent lamps and LED lamps are not equipped with advanced abilities both to regulate their electrical currents for better qualities or functions and to be compatible with various types of ballasts avoiding typical needs to find a suitable lamp when the fluorescent or LED lamp is not compatible with a present type of ballast. So, there are needs for an improved LED tube lamp which is compatible or can be used with, or can be supplied by, any of different power sources of external driving signal, including, e.g., an AC power line, an electrical ballast, and a DC power source.
Accordingly, the prevent disclosure and its embodiments are herein provided.